Blood products are pharmaceutical products generally comprising a human blood or a material obtained therefrom as effective components, and roughly classified into blood products for blood transfusion and fractionated plasma products. “The blood products for blood transfusion” are all of the human blood (whole blood) or preparations (component preparation) in which components such as red blood cell, platelet and plasma are separated from or adjusted to the human blood, and the component preparation has been mainly used at present. On the other hand, “the fractionated plasma products” are materials in which plasma proteins necessary for treatment are separated to each spices from human blood plasma and purified, and may be mentioned an albumin preparation, an immunoglobulin preparation and a blood coagulation factor preparation as main products.
The blood products for blood transfusion have been subjected to the treatment of removing leukocytes before preservation as a measure of safety. This has been done for the purpose of decreasing side effects such as a reaction of fever and infectious disease, caused by leukocytes. For the removal of the leukocytes before preservation, there are a mechanical removing method using a blood collecting apparatus and a filtering method using a leukocyte removing filter and, for example, it has been recommended to reduce a number of the leukocytes contained in one bag of the blood products for blood transfusion to 1×106 cells or less.
In particular, in the points of easiness in operation and a low cost, a filtering method using, as a filter material, a fibrous porous element such as nonwoven fabric or a nonfibrous porous element such as porous ceramic has widely been used. Also, to improve removing efficiency of leukocytes or recovery efficiency of platelets of these filter materials, various techniques to coat the surface of a filter material with a surface treatment agent have been reported.
As such a coating agent (a surface treatment agent), for example, a polymer having a nonionic hydrophilic group and a basic nitrogen-containing functional group, more specifically, a copolymer comprising 97 mol % of 2-hydroxyethyl(meth)acrylate and 3 mol % of N,N-dimethylaminoethyl(meth)acrylate has been reported (for example, see Patent Document 1). Similarly, a copolymer containing a monomer (A) having a hydrophilic functional group, a monomer (B) having a basic functional group and a monomer (C) having a reactive functional group as monomer components and constituted by predetermined molar ratios, more specifically, a copolymer containing 2-methoxyethyl acrylate (monomer (A)), N,N-dimethylaminoethyl methacrylate (monomer (B)) and 2-hydroxyethyl methacrylate (monomer (C)) as monomer components and constituted by predetermined molar ratios has been reported (for example, see Patent Document 2). The latter copolymer has been said that adhesion and activation of the platelets are suppressed by the monomers (A) and (B), the leukocytes are selectively adhered, further by the monomer (C), fixation of the surface treatment agent to the substrate is continued, and at the time of production and use, the surface treatment agent is never desorbed (eluted) from the substrate.
Contrary to the coating agent (the surface treatment agent) showing adhesion to the leukocyte as mentioned above, a substrate having a polymer material containing a cation and an anion at the side chain on the surface thereof has been known to have a function of preventing adhesion of biological substances (protein, cell, etc.) since the surface has been maintained to be electrically neutral due to the electrostatic balance. A coating material using these functions has been proposed and, in recent years, various reports have been made on the fixation or immobilization method to glass or a polymer substrate, etc. For example, a coating film obtained by subjecting a film formed by a coating solution containing a polymer having a phosphoric acid ester group to heat treatment at 200 to 450° C. has been reported to be excellent in durability while maintaining protein non-adhesion characteristics (for example, see Patent Document 3), and these are expected to be a coating material which suppresses adhesion of various biological substances in the medical instruments, equipments, etc.